Synchronous transmission pivot shaft device

ABSTRACT

A synchronous transmission pivot shaft device has a simplified structure and less assembled components and reduces assembling tolerance/motional space. The synchronous transmission pivot shaft device includes an assembly of a main body, a first operation board and a second operation board disposed on the main body. The first operation board has an obliquely extending arm section. The second operation board has an obliquely extending arm section. The arm sections of the first and second operation boards are respectively received in a first oblique rail and a second oblique rail of the main body. When a user operates the first operation board or the second operation board to move, the first operation board or the arm section thereof and the second operation board or the arm section thereof respectively synchronously move along the first and second oblique rails to achieve opening/closing effect.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to a pivot shaft structure, and more particularly to a synchronous transmission pivot shaft device, which employs oblique arm sections and cooperative oblique rails to achieve synchronously moving effect. Also, the synchronous transmission pivot shaft device has less assembled components and reduces assembling tolerance/motional space.

2. Description of the Related Art

There are various electronic apparatuses provided with covers or display screens, such as mobile phones, notebooks, PDA and electronic books. The covers or display screens are pivotally mounted on the electronic apparatuses via pivot pins or rotary shafts, whereby the covers or the display screens can be freely rotated and opened/closed under external force.

In order to operate the display module (such as the screen) and/or the apparatus body module of the electronic apparatus in more operation modes to widen the application range thereof, a conventional dual-shaft mechanism mounted between the display module and the apparatus body module has been developed to rotate the display module and/or the apparatus body module by different angles in accordance with different operation modes. For example, Taiwanese Patent No. 99211350 “dual-shaft hinge device”, Taiwanese Patent No. 99225737 “biaxial hinge device” and U.S. Pat. No. 7,512,426 B2 “mobile communications device with synchronizing hinge” disclose typical embodiments.

With respect to the operation, motion and structural design of such dual-shaft mechanism or pivot shaft assembly, in order to achieve synchronous transmission effect, practically at least one set of dual-shaft assembly in cooperation with the transmission mechanism must be used to make the display module and/or the apparatus body module move in different operation modes. For example, Taiwanese Patent No. 102216086 “synchronous moving device applied to dual-shaft system” and Taiwanese Patent No. 105126016 “pivot shaft device with displaceable shaft” disclose typical embodiments.

The conventional dual-shaft mechanism includes an assembly of multiple rotary shafts, gears and link plates for transmitting power, whereby the rotary shafts can synchronously rotate. In order to meet the requirements for lightweight and thin structure of the electronic apparatus, the rotary shafts and the relevant connection components and the gears and link plates for transmitting power are as minified as possible so that the electronic apparatus can have a simplified structure and beautiful appearance.

However, as well known by those who are skilled in this field, the minimization of the gears and link plates will lead to reduction of the engagement/transmission working depth between these components. As a result, the structural strength of the gears will be obviously weakened and the use lifetime of the gears will be shortened. This is unbeneficial to the cooperation and power transmission between the gears and often causes an idling travel due to rotational slippage. Also, the operational hand feeling of a user will be deteriorated.

Especially, when a user operates the display module to rotate, the multiple gears and link plates are driven to drive the rotary shafts, whereby the apparatus body module is driven to synchronously rotate. The rotary shafts are assembled with the multiple gears and link plates for transmitting power so that the structural relationship between these components is relatively complicated. These components are troublesome to assemble and the assembling tolerance is large. Also, these components have larger volume to occupy much room. This is not what we expect.

To speak representatively, the conventional dual-shaft mechanism or pivot shaft and the relevant connection components thereof have some shortcomings in use and structural design. The rotary shaft structure and the relevant components can be redesigned to eliminate the above shortcomings in operation and change the use form as well as widen the application range. For example, in condition that the requirement for lightweight and thin design of the electronic apparatus is satisfied and the pivot shaft device or the relevant components are such structurally designed as to synchronously move, the shortcoming of the conventional structure that the power transmission can be hardly smoothly performed to cause idling travel can be improved. In addition, the structural form of the dual-shaft system of the conventional pivot shaft device is omitted, whereby the display module and/or the apparatus body module can be synchronously move in different operation modes. Moreover, the pivot shaft device can be assembled with the electronic apparatus at higher transmission precision and stability. Also, the structure and assembling process are simplified and the shortcoming of the conventional structure that the cooperative components have larger volume to occupy more (motional) space. None of the above references specifically teaches, suggests or discloses the above issues.

SUMMARY OF THE INVENTION

It is therefore a primary object of the present invention to provide a synchronous transmission pivot shaft device has a simplified structure and less assembled components and reduces assembling tolerance/motional space. The synchronous transmission pivot shaft device includes an assembly of a main body, a first operation board and a second operation board disposed on the main body. The first operation board has an obliquely extending arm section. The second operation board has an obliquely extending arm section. The arm sections of the first and second operation boards are respectively received in a first oblique rail and a second oblique rail of the main body. When a user operates the first operation board or the second operation board to move, the first operation board or the arm section thereof and the second operation board or the arm section thereof respectively synchronously (or in reverse directions) move along the first and second oblique rails to achieve opening/closing effect. The synchronous transmission pivot shaft device of the present invention improves the shortcoming of the conventional dual-shaft pivot shaft device that the structure is complicated and it is troublesome to manufacture and assemble the components and the assembling tolerance is large and the structure is unbeneficial to the power transmission to cause idling travel.

In the above synchronous transmission pivot shaft device, the main body is an arched cylindrical body having a chamber with an arched (cross-sectional) structure. Multiple restriction sections are disposed or integrally formed in the chamber to define the first and second oblique rails.

In the above synchronous transmission pivot shaft device, the main body is disposed on a base seat. The base seat has a chamber for receiving the main body. The main body is permitted to reciprocally move within the chamber of the base seat. When the first operation board or the arm section thereof moves along the first oblique rail to one side, the main body is pushed to move from a first position (or open position) of the chamber to a second position (or closed position), whereby the second operation board or the arm section thereof is synchronously driven to move the second oblique rail to the other side.

The present invention can be best understood through the following description and accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the present invention, showing that the main body is assembled with the base seat and the first and second operation boards and the main body is positioned in the first position of the chamber of the base seat;

FIG. 2 is a perspective exploded view of the present invention according to FIG. 1, showing the structures of the main body, the base seat, the first and second operation boards and the restriction sections disposed on the main body;

FIG. 3 is a plane view of the present invention according to FIG. 1, showing that the first and second operation boards are positioned in the open position;

FIG. 4 is a perspective view of the operation of the present invention, showing that the first and second operation boards are moved from the open position to the closed position and the main body is moved from the first position to the second position;

FIG. 5 is a sectional view of the present invention according to FIG. 4, in which the phantom lines show that the first and second operation boards are assembled with a case and a screen and the first and second operation boards synchronously rotate around a virtual axis;

FIG. 6 is another perspective view of the operation of the present invention, showing that the first and second operation boards are positioned in the closed position and the main body is positioned in the second position; and

FIG. 7 is a sectional view according to FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 1, 2 and 3. The synchronous transmission pivot shaft device of the present invention includes an assembly of a main body 50, a first operation board 10 and a second operation board 20. The upper section, upper side, bottom section, lower side, left end, left side, right end, right side, etc. mentioned hereinafter are recited with the direction of the drawings as the reference direction.

As shown in the drawings, the main body 50 is an arched plate body or a cylindrical (or substantially semi-cylindrical) body. The main body 50 has an open chamber 55 with an arched (cross-sectional) structure. A diaphragm 56 is selectively disposed in a substantially middle position of the chamber 55 to partition the chamber 55 into a first (arched) cavity 58 and a second (arched) cavity 59. In addition, the upper side (with reference to the drawings) of the main body 50 is formed with a first notch 51 in communication with the first cavity 58. The lower side of the main body 50 is formed with a second notch 52 in communication with the second cavity 59. The first notch 51 is positioned in a position in adjacency to the diaphragm 56 (or in adjacency to the middle of the main body 50). The second notch 52 is positioned in a position distal from the diaphragm 56 (or distal from the middle of the main body 50).

In this embodiment, multiple restriction sections are disposed or integrally formed in the chamber 55. The restriction sections can be classified into first restriction section 30 and second restriction section 40 respectively positioned in the first and second cavities 58, 59. The first and second restriction sections 30, 40 are formed with multiple block bodies with arched cross section. A first oblique rail 31 is disposed in or defined by the first restriction section 30 in communication with the first notch 51. A second oblique rail 42 is disposed in or defined by the second restriction section 40 in communication with the second notch 52.

In a preferred embodiment, the first and second oblique rails 31, 42 respectively have the form of arched slot in adaptation to the arched (cross-sectional) structure of the main body 50 (or the chamber 55).

With the direction of the drawings as the reference direction, the first oblique rail 31 obliquely extends from the upper side (or the first notch 51) to the lower side and left end of the main body 50.

The second oblique rail 42 obliquely extends from the upper side to the lower side and right end of the main body 50 (or the second notch 52).

As shown in FIGS. 1, 2 and 3, the first and second operation boards 10, 20 are disposed on the main body 50. The first operation board 10 has an arched arm section 11 protruding from the first operation board 10. The second operation board 20 has an arched arm section 22 protruding from the second operation board 20. The arched arm sections 11, 22 of the first and second operation boards 10, 20 are respectively reciprocally movably received in the first and second oblique rails 31, 42 of the main body 10. In addition, the arched arm sections 11, 22 of the first and second operation boards 10, 20 respectively have connection ends 18, 28 and free ends 19, 29.

In this embodiment, the arm section 11 of the first operation board 10 obliquely extends from the connection end 18 to the free end 19 and the left end (with reference to the drawings) corresponding to the first oblique rail 31. The arm section 22 of the second operation board 20 obliquely extends from the connection end 28 to the free end 29 and the left end (with reference to the drawings) corresponding to the second oblique rail 42.

As shown in the drawings, the main body 50 can be assembled and disposed on a base seat 60. The base seat 60 is an arched plate body or a cylindrical (or substantially semi-cylindrical) body. The base seat 60 has an open chamber 61 with an arched (cross-sectional) structure for receiving the main body 50. The main body 50 is permitted to reciprocally move within the chamber 65 of the base seat 60. The upper side of the base seat 60 is formed with a first notch 61 corresponding to the first notch 51 of the main body. The lower side of the base seat 60 is formed with a second notch 62 corresponding to the second notch 52 of the main body.

In a preferred embodiment, an assembling section 54 in the form of an elongated raised structure (or elongated sunken structure) is disposed under the bottom section of the main body 50. A guide section 64 in the form of an elongated sunken structure (or elongated raised structure) is disposed in the chamber 65 of the base seat 60 corresponding to the assembling section 54 of the main body 50. Accordingly, when the main body 50 is mounted in the chamber 65 of the base seat, the assembling section 54 of the main body is assembled with the guide section 64 of the base seat, whereby the main body 50 can stably freely move within the chamber 65.

Please refer to FIG. 1 or 3, which show that the main body 50 is assembled with the base seat 60 and the first and second operation boards 10, 20 (and the first and second restriction sections 30, 40). The assembling positions are such defined that the main body 50 is positioned in a first position in the chamber 65 of the base seat and the first and second operation boards 10, 20 are positioned in an open position.

Please refer to FIGS. 4 and 5. The phantom lines of FIG. 5 show that the first and second operation boards 10, 20 are assembled with a case 70 and a screen 80. The screen 80 can be a flexible screen or a nonflexible screen. When a user operates the case 70 (or the screen 80), the first and second operation boards 10, 20 are moved from the open position to the closed position in a manner as follows:

-   1. The first operation board 10 or the arm section 11 of the first     operation board 10 and the second operation board 20 or the arm     section 22 of the second operation board 20 rotate around a virtual     axis C to respectively move along the first and second oblique rails     31, 42. Accordingly, the arm section 11 of the first operation board     10 is forced to gradually protrude from the first notch 51 (or the     first notch 61). At the same time, the main body 50 (or the first     and second restriction sections 30, 40) are driven to move from the     first position of the chamber 65 (or the right end of FIG. 4) to the     second position (or the left end of FIG. 4). It should be noted that     the virtual axis C is positioned at the center of the motional range     (or rotational range) of the arm section 11 of the first operation     board 10 and the arm section 22 of the second operation board 20. -   2. In response to the move of the second restriction section 40, the     second oblique rail 42 synchronously drives the arm section 22 of     the second operation board 20 to gradually protrude from the second     notch 52 (or the second notch 62).

Please now refer to FIGS. 6 and 7. When the first and second operation boards 10, 20 (or the case 70 and the screen 80) reach the closed position, the main body 50 also reaches the second position from the first position of the chamber 65. Accordingly, the first and second operation boards 10, 20 (or the case 70 and the screen 80) can be opened and closed.

It should be noted that the first and second oblique rails 31, 42 are curved and arranged along the virtual axis C. Also, the arched structures (or the curvature) of the arm section 11 of the first operation board 10 and the arm section 22 of the second operation board 20 are identical to the curvature of the first and second oblique rails 31, 42.

To speak representatively, in condition that the requirement for lightweight and thin (or simplified) design of the electronic apparatus is satisfied, in comparison with the conventional pivot shaft device, the synchronous transmission pivot shaft device of the present invention has the following advantages:

-   1. The assembling structures of the main body 50 and the first and     second operation boards 10, 20 or base seat 60 have been redesigned     to form a single-shaft structure capable of synchronously rotating     and/or moving. For example, the first and second restriction     sections 30, 40 are disposed on the main body 10 to form the first     and second oblique rails 31, 42. The first and second operation     boards 10, 20 are respectively formed with the arched protruding arm     sections 11, 22, which can reciprocally move along the first and     second oblique rails 31, 42. Also, the main body 50 can move between     the first and second positions in the chamber 65 of the base seat.     These are obviously different from the structural form of the     conventional dual-shaft pivot shaft device. -   2. The assembling structures of the main body 50 and the first and     second operation boards 10, 20 or the base seat 60 and the flexible     screen 80 are able to achieve a beautiful appearance of the entire     electronic apparatus and provide a simplified and beautified visual     effect, whereby the shortcoming of the conventional dual-shaft pivot     shaft device that the components have larger volume to occupy more     (gap/motional) space. Moreover, the shortcomings of the conventional     dual-shaft pivot shaft device that the structure is unbeneficial to     the power transmission to cause idling travel and the cooperative     form is more complicated and it is troublesome to manufacture and     assemble the components and the assembling tolerance is large and     the cost is high are obviously improved.

In conclusion, the synchronous transmission pivot shaft device of the present invention is effective and different from the conventional dual-shaft pivot shaft device in space form. The synchronous transmission pivot shaft device of the present invention is inventive, greatly advanced and advantageous over the conventional dual-shaft pivot shaft device.

The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from the spirit of the present invention. 

What is claimed is:
 1. A synchronous transmission pivot shaft device comprising: an assembly of a main body (50), a first operation board (10) and a second operation board (20) disposed on the main body (50), the main body (50) having a chamber (55), a first oblique rail (31) and a second oblique rail (42) positioned on the chamber (55), the first operation board (10) having a protruding arm section (11), the second operation board (20) having a protruding arm section (22), the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20) respectively having connection ends (18), (28) and free ends (19), (29), the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20) being respectively received in the first oblique rail (31) and the second oblique rail (42), whereby when the first operation board (10) and the second operation board (20) move, the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20) respectively synchronously move along the first oblique rail (31) and the second oblique rail (42).
 2. The synchronous transmission pivot shaft device as claimed in claim 1, wherein the first oblique rail (31) and the second oblique rail (42) respectively have the form of arched slot, the first oblique rail (31) obliquely extending from an upper side to a lower side and left end of the main body (50), the second oblique rail (42) obliquely extending from the upper side to the lower side and right end of the main body (50), the arm section (11) of the first operation board (10) obliquely extending from the connection end (18) to the free end (19) and the left end to form an arched protruding structure, the arm section (22) of the second operation board (20) obliquely extending from the connection end (28) to the free end (29) and the left end to form an arched protruding structure, the curvature of the arched structures of the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20) being equal to the curvature of the first oblique rail (31) and the curvature of the second oblique rail (42).
 3. The synchronous transmission pivot shaft device as claimed in claim 1, wherein the main body (50) is an arched plate body, whereby the chamber (55) is an open chamber with an arched cross-sectional structure, the upper side of the main body (50) being formed with a first notch (51), the lower side of the main body (50) being formed with a second notch (52), the first notch (51) being positioned in a position in adjacency to the middle of the main body (50), the second notch (52) being positioned in a position distal from the middle of the main body (50), a diaphragm (56) being in a middle position of the chamber (55) to partition the chamber (55) into a first cavity (58) and a second cavity (59), the first cavity (58) being in communication with the first notch (51), the second cavity (59) being in communication with the second notch (52).
 4. The synchronous transmission pivot shaft device as claimed in claim 2, wherein the main body (50) is an arched plate body, whereby the chamber (55) is an open chamber with an arched cross-sectional structure, the upper side of the main body (50) being formed with a first notch (51), the lower side of the main body (50) being formed with a second notch (52), the first notch (51) being positioned in a position in adjacency to the middle of the main body (50), the second notch (52) being positioned in a position distal from the middle of the main body (50), a diaphragm (56) being in a middle position of the chamber (55) to partition the chamber (55) into a first cavity (58) and a second cavity (59), the first cavity (58) being in communication with the first notch (51), the second cavity (59) being in communication with the second notch (52).
 5. The synchronous transmission pivot shaft device as claimed in claim 1, wherein multiple restriction sections are disposed in the chamber (55), the restriction sections being block bodies with arched cross section, the restriction sections being classified into first restriction section (30) and second restriction section (40), the first restriction section (30) defining the first oblique rail (31), the second restriction section (40) defining the second oblique rail (42).
 6. The synchronous transmission pivot shaft device as claimed in claim 2, wherein multiple restriction sections are disposed in the chamber (55), the restriction sections being block bodies with arched cross section, the restriction sections being classified into first restriction section (30) and second restriction section (40), the first restriction section (30) defining the first oblique rail (31), the second restriction section (40) defining the second oblique rail (42).
 7. The synchronous transmission pivot shaft device as claimed in claim 3, wherein multiple restriction sections are disposed in the chamber (55), the restriction sections being block bodies with arched cross section, the restriction sections being classified into first restriction section (30) and second restriction section (40) respectively positioned in the first cavity (58) and the second cavity (59), the first restriction section (30) defining the first oblique rail (31) in communication with the first notch (51), the second restriction section (40) defining the second oblique rail (42) in communication with the second notch (52).
 8. The synchronous transmission pivot shaft device as claimed in claim 4, wherein multiple restriction sections are disposed in the chamber (55), the restriction sections being block bodies with arched cross section, the restriction sections being classified into first restriction section (30) and second restriction section (40) respectively positioned in the first cavity (58) and the second cavity (59), the first restriction section (30) defining the first oblique rail (31) in communication with the first notch (51), the second restriction section (40) defining the second oblique rail (42) in communication with the second notch (52).
 9. The synchronous transmission pivot shaft device as claimed in claim 1, wherein the main body (50) is assembled and disposed on a base seat (60), the base seat (60) being an arched plate body having an open chamber (61) with an arched cross-sectional structure, the main body (50) being permitted to reciprocally move within the chamber (65) of the base seat (60), when the arm section (11) of the first operation board (10) rotates along the first oblique rail (31) to one side of the main body (50), the main body (50) being pushed to move from a first position of the chamber (65) to a second position, whereby the arm section (22) of the second operation board (20) is synchronously driven to rotate along the second oblique rail (42) to the other side of the main body (50), an upper side of the base seat (60) being formed with a first notch (61), a lower side of the base seat (60) being formed with a second notch (62), an assembling section (54) being disposed under the bottom section of the main body (50), the assembling section (54) being in the form of an elongated raised structure or an elongated sunken structure, a guide section (64) being disposed in the chamber (65) of the base seat (60), the guide section (64) being in the form of an elongated sunken structure or an elongated raised structure.
 10. The synchronous transmission pivot shaft device as claimed in claim 2, wherein the main body (50) is assembled and disposed on a base seat (60), the base seat (60) being an arched plate body having an open chamber (61) with an arched cross-sectional structure, the main body (50) being permitted to reciprocally move within the chamber (65) of the base seat (60), when the arm section (11) of the first operation board (10) rotates along the first oblique rail (31) to one side of the main body (50), the main body (50) being pushed to move from a first position of the chamber (65) to a second position, whereby the arm section (22) of the second operation board (20) is synchronously driven to rotate along the second oblique rail (42) to the other side of the main body (50), an upper side of the base seat (60) being formed with a first notch (61), a lower side of the base seat (60) being formed with a second notch (62), an assembling section (54) being disposed under the bottom section of the main body (50), the assembling section (54) being in the form of an elongated raised structure or an elongated sunken structure, a guide section (64) being disposed in the chamber (65) of the base seat (60), the guide section (64) being in the form of an elongated sunken structure or an elongated raised structure.
 11. The synchronous transmission pivot shaft device as claimed in claim 3, wherein the main body (50) is assembled and disposed on a base seat (60), the base seat (60) being an arched plate body having an open chamber (61) with an arched cross-sectional structure, the main body (50) being permitted to reciprocally move within the chamber (65) of the base seat (60), when the arm section (11) of the first operation board (10) rotates along the first oblique rail (31) to one side of the main body (50), the main body (50) being pushed to move from a first position of the chamber (65) to a second position, whereby the arm section (22) of the second operation board (20) is synchronously driven to rotate along the second oblique rail (42) to the other side of the main body (50), an upper side of the base seat (60) being formed with a first notch (61) corresponding to the first notch (51) of the main body, a lower side of the base seat (60) being formed with a second notch (62) corresponding to the second notch (52) of the main body, an assembling section (54) being disposed under the bottom section of the main body (50), the assembling section (54) being in the form of an elongated raised structure or an elongated sunken structure, a guide section (64) being disposed in the chamber (65) of the base seat (60), the guide section (64) being in the form of an elongated sunken structure or an elongated raised structure.
 12. The synchronous transmission pivot shaft device as claimed in claim 5, wherein the main body (50) is assembled and disposed on a base seat (60), the base seat (60) being an arched plate body having an open chamber (61) with an arched cross-sectional structure, the main body (50) being permitted to reciprocally move within the chamber (65) of the base seat (60), when the arm section (11) of the first operation board (10) rotates along the first oblique rail (31) to one side of the main body (50), the main body (50) being pushed to move from a first position of the chamber (65) to a second position, whereby the arm section (22) of the second operation board (20) is synchronously driven to rotate along the second oblique rail (42) to the other side of the main body (50), an upper side of the base seat (60) being formed with a first notch (61), a lower side of the base seat (60) being formed with a second notch (62), an assembling section (54) being disposed under the bottom section of the main body (50), the assembling section (54) being in the form of an elongated raised structure or an elongated sunken structure, a guide section (64) being disposed in the chamber (65) of the base seat (60), the guide section (64) being in the form of an elongated sunken structure or an elongated raised structure.
 13. The synchronous transmission pivot shaft device as claimed in claim 6, wherein the main body (50) is assembled and disposed on a base seat (60), the base seat (60) being an arched plate body having an open chamber (61) with an arched cross-sectional structure, the main body (50) being permitted to reciprocally move within the chamber (65) of the base seat (60), when the arm section (11) of the first operation board (10) rotates along the first oblique rail (31) to one side of the main body (50), the main body (50) being pushed to move from a first position of the chamber (65) to a second position, whereby the arm section (22) of the second operation board (20) is synchronously driven to rotate along the second oblique rail (42) to the other side of the main body (50), an upper side of the base seat (60) being formed with a first notch (61), a lower side of the base seat (60) being formed with a second notch (62), an assembling section (54) being disposed under the bottom section of the main body (50), the assembling section (54) being in the form of an elongated raised structure or an elongated sunken structure, a guide section (64) being disposed in the chamber (65) of the base seat (60), the guide section (64) being in the form of an elongated sunken structure or an elongated raised structure.
 14. The synchronous transmission pivot shaft device as claimed in claim 7, wherein the main body (50) is assembled and disposed on a base seat (60), the base seat (60) being an arched plate body having an open chamber (61) with an arched cross-sectional structure, the main body (50) being permitted to reciprocally move within the chamber (65) of the base seat (60), when the arm section (11) of the first operation board (10) rotates along the first oblique rail (31) to one side of the main body (50), the main body (50) being pushed to move from a first position of the chamber (65) to a second position, whereby the arm section (22) of the second operation board (20) is synchronously driven to rotate along the second oblique rail (42) to the other side of the main body (50), an upper side of the base seat (60) being formed with a first notch (61) corresponding to the first notch (51) of the main body, a lower side of the base seat (60) being formed with a second notch (62) corresponding to the second notch (52) of the main body, an assembling section (54) being disposed under the bottom section of the main body (50), the assembling section (54) being in the form of an elongated raised structure or an elongated sunken structure, a guide section (64) being disposed in the chamber (65) of the base seat (60), the guide section (64) being in the form of an elongated sunken structure or an elongated raised structure.
 15. The synchronous transmission pivot shaft device as claimed in claim 1, wherein the first and second operation boards (10), (20) are assembled with a case (70) and a screen (80), the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20) move around a virtual axis (C), the virtual axis (C) is positioned at a center of the motional range of the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20).
 16. The synchronous transmission pivot shaft device as claimed in claim 2, wherein the first and second operation boards (10), (20) are assembled with a case (70) and a screen (80), the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20) move around a virtual axis (C), the virtual axis (C) is positioned at a center of the motional range of the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20).
 17. The synchronous transmission pivot shaft device as claimed in claim 3, wherein the first and second operation boards (10), (20) are assembled with a case (70) and a screen (80), the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20) move around a virtual axis (C), the virtual axis (C) is positioned at a center of the motional range of the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20).
 18. The synchronous transmission pivot shaft device as claimed in claim 5, wherein the first and second operation boards (10), (20) are assembled with a case (70) and a screen (80), the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20) move around a virtual axis (C), the virtual axis (C) is positioned at a center of the motional range of the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20).
 19. The synchronous transmission pivot shaft device as claimed in claim 9, wherein the first and second operation boards (10), (20) are assembled with a case (70) and a screen (80), the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20) move around a virtual axis (C), the virtual axis (C) is positioned at a center of the motional range of the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20).
 20. The synchronous transmission pivot shaft device as claimed in claim 14, wherein the first and second operation boards (10), (20) are assembled with a case (70) and a screen (80), the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20) move around a virtual axis (C), the virtual axis (C) is positioned at a center of the motional range of the arm section (11) of the first operation board (10) and the arm section (22) of the second operation board (20). 